User interface for a display screen on the top of a portable computer



The FIGURE is a front view of a user interface for a portion of a display screen of the top of a portable computer showing my new design.

The broken line showings of the regions inside the user interface, the external display screen, and the top of a portable computer are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for an user interface for a display screen on the top of a portable computer, as shown and described. 